Future gigantic solar farms might impact solar power elsewhere in the world

Their model: Put all of those solar panels in Northern Africa!!!

In this extreme scenario, yes, their are possible impacts. Since, such an extreme scenario is unlikely to happen, this is only an intellectual exercise.

Paper link: https://www.nature.com/articles/s43247-023-01117-5

To give you an idea of the climate impact, according to the World Bank website, all urban areas on Earth total to ~2 M km2. So we have already built at least 5x the area of this imaginary solar array.

   "And in any case, these effects are based on hypothetical scenarios. Our Sahara scenario was based on covering 20% of the entire desert in PV solar farms, for instance, and though there have been ambitious proposals, anything on that scale is unlikely to happen in the near future. If the covered area is reduced to a more plausible (though still unlikely) 5% of the Sahara, the global effects become mostly negligible."

The negative harms should be studied, but also balanced rationally.

We need to have a wider / deeper discussion about the relative harms vs benefits of solar "geo-engineeering" - putting particulates or salt water droplets into the air to reflect sunlight, to reduce warming.

This is urgent - the CO2 is already there, and we will likely have a long plateau of current highest emissions for another decade .. its the area under that curve that matters - total CO2 - and this will likely bake in +2C in coming years.

We have some data from vulcanic eruptions and recent reduction of particulates in shipping fuel, so we know in principle it works.

We've been releasing sulphites inadvertently as pollution for a long time .. it has not been world ending.

We need to do experiments and get better estimates on the benefit and harms, and feed that back into our climate models, and climate and weather predictions if we do larger geoengineering.

If we stopped all carbon burning tomorrow, we still need a way to bring the heat down - the ice and sea have buffered a great deal of the damage, but the ice will keep melting for a long time from current GHGs, perhaps irreversibly on human time scales. Id argue that harm is orders of magnitude greater than the negative effects of releasing sun-reflecting/shielding particulates.

To act or not, which does more harm ? That is a question science can give the best answers to. We need to get over the 'controversy', do the science we can in the short time we have and then act.

This seems, though, if anything (and, of course maybe it is nothing), to be an argument for not putting all of the panels in one desert. Which is fine. Actually it would be nice to put renewables everywhere so regions can be energy-independent.

Meaning: solar modules do absorb heat, but they are normally not ON GROUND, they are a bit lifted, so the heat they absorb during the day get quickly dispersed by the atmosphere during the night, they thermal mass is little, making days a bit more hot in the air, but similarly shielding the sand underneath to get hot, since it's shaded by the modules and that makes night a bit cooler since the sand have much more thermal mass. This circadian delta might accelerate air circulation, witch might move differently the whole earth atmosphere but simulating the substantial effects seems a bit too much for our modeling capacity, too many variables, too much possible drifts.

Floating solar seems to make good sense; the 'land' is otherwise unused and unusable, the water can be used for cooling, it offers shade and a structure for marine life. Of course cabling and storm-proofing etc means much more expense, but if we're talking about gigantic installations ...

https://web.archive.org/web/20091122081412/http://origin.the...

Given how much the Brits whinge about anything over 24°C, as an Australian I think it's our duty to the world to do this.

i haven't read the paper, so i don't know what fill factor they're considering. say it's 50%, so the spaces between the panels occupy as much area as the panels

9.2 million sq km · 20% occupancy · 50% fill factor · 21% efficiency · 29% capacity factor (which is probably a bit low) · 1000 watts/m² works out to average production of 56 terawatts, roughly three times current global marketed energy consumption, which is 18 terawatts

that is, building such a thing involves quadrupling the energy budget per person. right now the humans use about 18 terawatts, about 2.25 kilowatts per person, roughly equivalent to the labor of 22 workers. we're talking about boosting that to 10 kilowatts, so the average person has the equivalent of 100 laborers at their disposal, so it will be a vast reduction in the cost of energy

and the sahara isn't the only place you can put solar panels, even on earth, even on land

what would a human society that's four times as energy-intensive look like

they also say that if you only cover 5% of the sahara in solar panels, so that this one power plant produces more energy than the entire human race does today, 'the global effects become mostly negligible'

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in the other direction, consider their opening declaration, 'the sun's energy is effectively limitless.' the sun only outputs 380 yottawatts, which is only greater than the 18-terawatt number above by a factor of 21 trillion. so human energy consumption can only grow by 21 trillion times before finding other, larger energy sources

okay but is that a lot or what

if we take the historical post-industrial-revolution growth rate of 5 percent per year and apply it to energy consumption (perhaps on the assumption that there's a lower limit to how much energy we can dissipate per unit of value produced, even if we haven't reached that limit yet) that's only 629 years of growth. that's longer than a human lifetime but still an eyeblink in the two-million-year story of humanity or the ten-thousand-year span of recorded history

if, by contrast, we start building von neumann replicators that mine mars and venus in order to double their population and energy consumption on average every year, it's only 44 years, and many people still alive will see it happen

so i think 'effectively limitless' is shortsighted

I have no idea how significant the effect would be, but it would be an interesting study to do / read.

Mind wanders off to solar installations in space which pops up in mainstream press a few times a year.

Is there a way to make them, say, white?

Next up: gigantic wind farms change weather.

Further up: we need to reduce our energy consumption, or vent excess heat directly into space. Give it another 10 years or so. CO² is a relevant and dominant factor in global warming, but I'd bet a lot of money that it isn't the only one, just the dominant one we know of right now.

By the way: the amount of surplus heating currently observed in the oceans exceeds the predicted amount by around two orders of magnitude. Too tired to provide (indirect) sources. At least this was my understanding by following the traces of for example this article¹.

¹ https://www.theguardian.com/environment/2024/jan/08/global-t...

So we should obviously just keep doing that...